Human eyes are the organs of vision. They sense the light and convert it into electro-chemical impulses in neurons, so as to create a vivid vision in the brain. The eye (eyeball) is only one inch in diameter but a complex optical system. It collects light from the surrounding environment, regulates its intensity through the pupil, focuses it through an adjustable assembly of lenses, and forms an image on the retina.
However, according to some studies, in the modern world about 80% of the population suffers from different vision impairments/disorders caused by refractive error, wherein an optical state of the eye in which the focus of the eye is incorrect causing blurred vision, includes myopia, hyperopia (far-sightedness or long-sightedness) and refractive astigmatism. Among these errors, myopia or the so-called nearsightedness becomes more and more prevalent. Particularly, myopia is the most common eye problem among children and young adults in many countries, especially in Asian countries, such as China, as education systems become more demanding, and electronic display devices become increasingly popular and prevalent.
In cases of myopia, the visual focus defect is such that distant objects (items in the scenery being viewed by the eye) appear blurred because their images are focused in front of the retina instead of on the retina. Myopia brings inconvenience to the people. In particular, people with relatively low degrees of myopia usually require an optical correction (spectacles or contact lenses) to allow them to drive a car or see the school blackboard, whereas those with high myopia also have an increased risk of developing blinding conditions such as retinal detachment and glaucoma.
Various classification systems have been described for myopia, and the following classification is commonly used by clinical entity, in which different myopia types are classified by their causes:                Simple myopia (also called school myopia) is usually caused by extensive vision stress such as long time reading, study, near works, and etc., and is far more common than any other type of myopia, which affects about 30% of population.        Pseudomyopia refers to an intermittent and temporary shift in refraction of the eye towards myopia, in which the focusing of light in front of the retina is due to overstimulation of the eyes' accommodative mechanism or ciliary spasm.        Degenerative myopia, also known as malignant, pathological, or progressive myopia, is characterized by marked fundus changes, such as posterior staphyloma, and associated with a high refractive error and subnormal visual acuity after correction.        Nocturnal myopia, also known as night or twilight myopia, is a condition in which the eye has a greater difficulty seeing in low-illumination areas, even though its daytime vision is normal.        Induced myopia, also known as acquired myopia, results from exposure to various pharmaceuticals or toxic chemicals, increases in glucose levels, nuclear sclerosis, oxygen toxicity (e.g., from diving or from oxygen and hyperbaric therapy) or other anomalous conditions.        
Simple myopia, degenerative myopia, and induced myopia are called physiological myopia with structure defects on the eyes, contrary to pseudomyopia, which can be restored if treated promptly, especially for young adults and children.
In the art, there are several ways to correct myopia, among which the following three methods are most popular:                1) To provide ophthalmic lenses (spectacles and contact lenses) with proper negative or minus diopters which optically change the position of the focus of the visual image so the image is lying on the retina;        2) To conduct refractive surgery on the eyeballs so as to physically decrease the optical power of the cornea or of the crystalline lens and thus let the light focus on the retina and restore a clear vision; and        3) To prescribe pharmacological agents such as atropine or pirenzipine especially for pseudomyopia, in which the focusing of light in front of the retina is due to a transient spasm of the ciliary muscle causing an increase in the refractive power of the eye.        
However, the first two methods do little to slow or stop the progression of myopia, and, according to at least some research findings, they may even actually promote the progression of myopia. As for the third method, the potential disadvantages associated with the long-term use of such pharmacological substances may render such modalities unattractive.
Therefore, methods and systems for inhibiting myopia, especially at an earlier stage, have been widely studied. People found that both genetic and environmental (intensive and excessive near work) factors may contribute to the cause and the development of myopia, and most studies show that the environmental factor plays a predominant role. It is proven that excessive near work needs prolonged muscular effort of focusing the eyes at near (accommodation) which results in a lag of accommodation (insufficient accommodation) and hyperopic retinal defocus (behind the retina), which may change the structure of the eye, such as an increase of axial length of the eyeball, and thus permanently result in the physiological myopia and its progression.
Furthermore, there is one widely acknowledged theory, lag and lead of accommodation theory, for explaining the relationship between accommodation and the cause of myopia. It is known that when subjects look at a given object, through the mechanism of accommodation, the curvature of the crystalline lens is changed and therefore the power of the eye, allowing generally a clear vision of the object. However, due in particular to the depth of field of the eye and the tolerance to blur of the human visual system, the amount of accommodation is most of the time not the theoretical value, for example theoretically, for an object at 40 cm, the accommodation value should be 2.5 diopters. When the accommodation is less than the calculated accommodation, it is called a lag of accommodation. If the accommodation is higher than what is theoretically needed, it's called a lead of accommodation. It is believed that the lag of accommodation (insufficient accommodation) may induce myopia progression through retinal hyperopic defocus.
On the basis of this theory, studies have found lenses with plus addition could provide clear vision with less accommodation during near viewing, thereby preventing myopia or slowing the progression of myopia, since additions or near additions reduce the lag of accommodation (insufficient accommodation).
In this regard, standard near additions have been used for decades to slow myopia progression or to prevent its onset especially for children and young adults.
In some studies (Leung & Brown, 1999; Edwards et al., 2002; Gwiazda et al, 2003; etc.), it is shown that the success of the standard near additions is limited considering all children. In some specific subgroups of children, their effect was significant, for example near esophores with high lags of accommodation. Moreover, even in those subgroups, fixed additions had a better efficacy in some children compared to others. One possible explanation for the lack of efficacy in some children compared to others is that the standard addition value is not adapted for each child, especially considering their effect on the child's binocular vision. Therefore, if the addition is too high, the child will not use it. If the addition is too low, it will have insufficient impact on the lag of accommodation and its efficacy will also be reduced.
U.S. Pat. No. 8,511,819 B2 also describes a method for preventing the onset of myopia, consisting of prescribing a pair of glasses with a standard addition of +2.00 diopters. However, the addition value is fixed and its efficacy should therefore be limited as described above.
However, the above studies mainly consider the accommodative response only and are silent about the binocular conditions, such as convergence responses, like near phoria compensation, which may lead to discomfort.
To this end, some scientific articles have investigated methods to determine the addition value by considering both accommodative and convergence responses for binocular vision, which either strongly reduces the lag of accommodation or brings the near phoria into a “normal” domain. Jiang et al. (2008) suggested two formulas. One based on one lag of accommodation measurement and another based on one phoria measurement to determine the optimal addition value to slow myopia progression.
However, it is still not clear if such addition value is well tolerated by the child in terms of binocular vision, especially in terms of motor and sensory fusion, or if it is high enough to have an effect on myopia progression.
Therefore, none of the prior art provides a comprehensive, simple and effective method or system to determine a personalized near addition value suited for myopes or non-presbyopes especially for children or young adults.